package com.xudow.app.util;

public class LngLatUtil {

    /**
     * 计算地球上任意两点(经纬度)距离
     *
     * @param long1 第一点经度
     * @param lat1  第一点纬度
     * @param long2 第二点经度
     * @param lat2  第二点纬度
     * @return 返回距离 单位：米
     */
    public static double distance(double long1, double lat1, double long2,
                                  double lat2) {
        double a, b, R;
        R = 6378137; // 地球半径
        lat1 = lat1 * Math.PI / 180.0;
        lat2 = lat2 * Math.PI / 180.0;
        a = lat1 - lat2;
        b = (long1 - long2) * Math.PI / 180.0;
        double d;
        double sa2, sb2;
        sa2 = Math.sin(a / 2.0);
        sb2 = Math.sin(b / 2.0);
        d = 2
                * R
                * Math.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat1)
                * Math.cos(lat2) * sb2 * sb2));

        return d;
    }

    public static String distanceFormatted(double long1, double lat1, double long2,
                                           double lat2) {
        String ret;

        long distance = Math.round(distance(long1, lat1, long2, lat2));

        long kilometers = distance / 1000; //千米
        long meters = distance % 1000; //米

        if (kilometers <= 0) {
            ret = distance + "m";
        } else {
            //不足1千米的米转成类似于0.3的形式
            double meterDecimal = meters / 1000.0;
            ret = String.format("%.1fKm", (kilometers + meterDecimal));
        }

        return ret;
    }

}
